Air supply connection for pyrometer assembly on rotary kiln



H. D- PRESZLER Filed Jan. 8, 1968 AIR SUPPLY CONNECTION FOR PYROMETER ASSEMBLY ON ROTARY KILN Oct. 14, 1969 United States Patent O F US. Cl. 263 -33 12 Claims ABSTRACT OF THE DISCLOSURE In a rotary kiln, a radiation pyrometer is mounted on the kiln and communicates with the interior of the kiln through a sight passage extending through the kiln wall. An air projecting means such as a blower is connected by a duct to the sight passage and provides an air flow therethrough. The duct from the air projecting means is connected to the sight passage in such manner as to provide an .air flow having a substantial radially outward component of motion toward the pyrometer whereby to cause a localized turbulent air condition which prevents the settling of particles of material on the pyrometer lens or window. The radially outward air flow also provides an improved cooling effect on the pyrometer.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to temperature measurement in rotary kilns, and more particularly to a pyrometer and sight tube assembly connected to a forced air supply.

Description of the prior art This invention may be considered an improvement on the disclosure of United States Patent 3,345,873 issued to Otto G. Lellep on Oct. 10, 1967, entitled Rotary Kiln Temperature Measurement. In the disclosure of the Lellep patent, a radiation pyrometer is mounted on the outside of the kiln shell in an enlarged section of duct work which connects to an air blower and also to a sight hole extending through the kiln shell. The air stream supplied by the blower in the Lellep patent passes through the duct work and through the sight hole or tube into the inside of the kiln and in so doing helps to keep the sight hole free from processed material, dust, and combustion gases, and, at the same time, helps protect the pyrometer from becoming overheated.

A problem which is frequently encountered in the operation of rotary kilns having pyrometers with associated sight tubes, as in the aforementioned Lellep patent, is that the material being processed frequently passes into the sight tube and into contact with the pyrometer lens despite the presence in the sight tube of an air stream moving through the sight tube into the kiln. These particles of material frequently settle upon the pyrometer lens and prevent a proper passage of radiant energy from the interior of the kiln to the pyrometer lens, causing erroneous readings.

SUMMARY OF THE INVENTION Accordingly it is an object of the present invention to provide in combination with a pyrometer and sight tube for a rotary kiln or the like an air supply connection or 3,472,497 Patented Oct. 14, 1969 arrangement which prevents coating of the pyrometer lens or window with particles of the material being processed.

It is another object of the invention to provide an air supply connection for the sight tube of a pyrometer on a rotary kiln or the like which causes a turbulent air condition contiguous the pyrometer lens or window to prevent the deposit of particles of material on the lens or window.

It is another object of the invention to provide a pyrometer and sight tube arrangement for a rotary kiln which includes an improved cooling arrangement for the pyrometer.

In achievement of these objectives there is provided in accordance with this invention a combined pyrometer and sight tube for a rotary kiln or the like in which the air entering the sight tube from the blower or air projecting means is directed toward the lens or window of the pyrometer With a substantial radially outward component of motion in such a manner as to provide a continuous air turbulence contiguous the lens or window which entrains the particles of material in the air flow before they reach the pyrometer lens or window, the entrained particles being carried by the air flow through the sight tube into the kiln and away from the lens or window of the pyrometer. The direction of air flow toward the pyrometer lens or window also provides an improved cooling effect on the pyrometer and the elements thereof.

Further objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawing in which:

BRIEF DESCRIPTION OF THE DRAWING The sole figure is a view in section showing a pyrometer and sight tube assembly mounted on the wall of a rotary kiln or the like and connected to an air projecting means such as a blower by a connection which provides a turbulent air condition contiguous the pyrometer lens or window.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, there is shown a rotary kiln generally indicated at 10 which may be generally similar, for example to the rotary kiln shown in the United States Patent 2,728,146, issued to Benjamin L. Cody on Dec. 27, 1955. Reference is also made to United States Patent 3,273,874, issued to Ernest Hucke on Sept. 20, 1966, for a showing of a typical kiln used in cement manufacturing. The rotary kiln includes an outer shell 12 and a refractory wall 14. The pyrometer and sight tube assembly is generally indicated at 16 and. comprises a sight tube 18 which extends through a passage 20' in the kiln wall. The sight tube 13 projects radially outwardly beyond the outer shell 12 of the kiln and is provided at its radially outermost end with a flange 22 on which a radiation pyrometer generally indicated at 24 is mounted. For purposes of this application, a radiation pyrometer is hereby defined as a temperature sensitive instrument which will measure the temperature of an object or substance at a distance without making physical contact with the object or substance. The radiation pyrometer 24 is open at the radially inner end thereof adjacent flange 22, and a lens 25 is suitably mounted in the open end of the pyrometer to close the opening. Radiant energy which reaches lens 25 through sight tube 18 is focused by the lens onto temperature sensing element 26 of the pyrometer. The signal of sensing element 26 is conducted to an external control circuit through conductors 29 which are attached to slip rings on the outer surface of the kiln, the slip rings engaging brushes connected to the external circuit.

While the pyrometer 24 has been shown as having a lens 25, it is within the contemplation of this invention that the pyrometer might be of a type not requiring a lens, but prov1ded only with a Window-like end member of suitable material, mounted where lens 25 is shown.

An air projecting means in the form of a blower 27 driven by an electric motor 28 is suitably mounted on the outer wall 12 of the kiln. Blower 27 includes a discharge outlet 30 which is connected by a duct generally indicated at 32 to the interior of the sight tube 18. The duct 32 in the illustrated embodiment includes a section 34 which is suitably attached to the discharge outlet 30 of the blower. In accordance with an important feature of the construction, duct 32 also includes a section 3 6 which is connected to sight tube 18 contiguous the connection of pyrometer 24, section 36 of the duct 32 being connected to sight tube 18 in a radially outwardly inclined direction at an angle which in the illustrated embodiment is substantially 45 degrees with respect to the longitudinal axis of sight tube 18. While the angle of duct section 36 has been described and shown as being inclined radially outwardly at an angle of substantially 45 degrees relative to the longitudinal axis of sight tube 18, duct section 36 could be at any angle which causes air to be directed with a substantial radially outward component of motion toward the pyrometer. Due to the location and radial outward direction of entry of duct section 36 relative to sight tube 18, the air from blower 27 passing outwardly from duct section 36 into sight tube 18 at first flows radially outwardly at an angle toward the lens 25 of pyrometer 24. The air then changes direction to fiow radially inwardly through sight tube 18, and into the interior of kiln 10. The air flow just described creates a turbulent condition of the air contiguous lens 25, causing any particles of material in sight tube 18 adjacent the region of the pyrometer lens to be entrained in the turbulent air.

The material which is being processed is usually in a rather powdery state when it reaches the zone at which the pyrometer is located. Hence any particles of the material which pass from the kiln into sight tube 18 are of a powdery nature and are thereby easily entrained in the turbulent air just mentioned adjacent the pyrometer lens. The air in flowing radially inwardly from the turbulent region into the interior of the kiln carries with it the particles of material entrained in the air at the turbulent region.

The air which is directed toward the pyrometer and pyrometer lens in the radially outward direction not only creates the turbulent condition which entrains the particles of material just described, but also serves to cool the pyrometer lens and the other portions of the pyrometer. The air stream by preventing the deposit of particles of material on the pyrometer lens or window keeps the lens or window clean for better reception of the radiant energy from the interior of the kiln. In passing through the sight tube to the interior of the kiln, the air stream removes particles of material which have entered the sight tube, including those caught in the turbulent air flow, thereby insuring an unobstructed passage of the radiant energy to the pyrometer lens.

It can be seen from the foregoing that there has been provided in accordance with this invention an apparatus for and method of conducting forced air into the interior of a sight tube, and into proximity to a pyrometer mounted on the sight tube, in such manner as to substantially prevent the deposit of any particles of material on the lens or window of the pyrometer and also in such manner as to remove from the sight tube particles of material which have entered therein. The forced air at the same time due to its radially outward direction of flow, provides a cooling elfect on the pyrometer and on the elements thereof.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination, a rotary kiln through which a material passes while being heated to elevated temperature, a radiation pyrometer mounted on the outside of said kiln for rotation therewith, means forming a passage communicating the interior of said kiln with said pyrometer whereby to permit said pyrometer to receive radiation from the kiln interior through said passage, means operating to project an air stream through said passage, duct means connecting the air projecting means in fluid communication with said passage, said duct means at its junction with said passage being inclined to said passage'in a direction having a substantial radially outward component relative to said kiln whereby to direct air with a substantial radially outward component of motion toward said pyrometer.

2. The combination defined in claim 1 in which said pyrometer includes a lens, said duct means being positioned to direct air with a substantial radially outward component of motion toward said lens.

3. The combination defined in claim 1 in which said pyrometer includes a window through which radiant energy passes to a sensing element within the pyrometer, said duct means being positioned to direct air witha substantial radially outward component of motion toward said window.

4. The combination defined in claim 1 in which said means forming a passage comprises a sight tube.

5. The combination defined in claim 1 in which said means forming a passage comprises a sight tube and said pyrometer is secured to the radially outer end of said sight tube.

6. The combination defined in claim 1 in which said means forming a passage comprises a sight tube, said pyrometer being secured to the radially outer end of said sight tube, air duct means connecting said air projecting means to said sight tube, said duct means being positioned to direct air with a substantial radially outward component of motion toward said pyrometer.

7. The combination defined in claim 6 in which said pyrometer includes a lens, an air duct means connecting said air projecting means to said sight tube, said air duct means being positioned to direct air with a substantial radially outward component of motion toward said lens.

8. The combination defined in claim 6 in which said pyrometer includes a window through which radiant energy passes to a sensing element within the pyrometer, an air duct means connecting said air projecting means to said sight tube, said air duct means being positioned to direct air with a substantial radially outward component of motion toward said window.

9. A pyrometer and air supply assembly for a rotary kiln or the like, comprising a radiation pyrometer adapted to be mounted on the outside of the kiln for rotation therewith, means adapted to form a passage communicating the interior of the kiln with said pyrometer whereby to permit said pyrometer to receive radiation from the kiln interior through the passage, means operating to project an air stream through said passage, duct means connecting the air projecting means in fluid communication with said passage, said duct means at its junction with said passage being inclined to said passage in a direction having a substantial radially outward component relative to said kiln whereby to direct air with a substantial radially outward component of motion toward said pyrometer.

10. A pyrometer and air supply assembly for a rotary kiln or the like as defined in claim 9 in which said pyrometer includes a lens, said duct means being positioned to direct air with a substantial radially outward component of motion toward said lens.

11. A pyrometer and air supply assembly for a rotary kiln or the like as defined in claim 9 in which said pyrometer includes a window through which radiant energ passes to a sensing element within the pyrometer, said duct means being positioned to direct air with a substantial radially outward component of motion toward said window.

12. A pyrometer and air supply assembly for a rotary kiln or the like as defined in claim 9 in which the means forming a passage comprises a sight tube and said pyrometer is secured to the radially outer end of said sight tube.

References Cited UNITED STATES PATENTS Mead. Vollrath. Lellep. Lellep.

JOHN J. CAMBY, Primary Examiner US. Cl. X.R. 

